The present invention relates to a method for adjusting the colors of a polychrome plasma panel. It also relates to plasma panels using such a method.
Plasma panels are well known in the prior art. At the present time, the plasma panels which are commercialized are all monochrome, i.e. they emit light of a single color, which is usually orangey red.
Studies are being carried out in numerous research laboratories for improving polychrome panels.
To form polychrome panels it is known to dispose luminophores (luminescent materials) of different colors inside each panel. Each elementary image point of the panel is then formed by the juxtaposition of several zones of small size covered with luminophores of different colors and each of these zones corresponds to the intersection of electrodes receiving control signals.
The display of information on a plasma panel is achieved by creating luminescent discharges within a gas, contained in the space between two glass plates carrying the electrodes of the panel. The ultraviolet rays emitted during discharges excite the luminophore covered zones. The luminophores then emit by photoluminescence a visible light whose color is determined by the nature of the luminophore. Generally two or three luminophores of different colors are used, which makes it possible to obtain respectively one or four additional colors. Thus, for example, in the case of a panel in which each elementary image point comprises three zones covered with three different luminophores, respectively of red, green and blue colors, it is possible to further obtain yellow by combining the light emitted by the red and green luminophores, cyan by combining green and blue, magenta by combining red and blue and white by combining red, green and blue.
A problem arises in polychrome plasma panels which is that of balancing the basic colors, namely the colors coming from a single luminophore, so as to obtain exactly the desired shades of color when several of these basic colors are combined by simultaneously exciting several luminophores.
At the present time, adjustment of the colors of a panel is provided, as a function of the light and colorimetric characteristics of each of the luminophores used, by the geometry of the luminophore covered zones and by their number inside each elementary image point.
The possibilities of balancing the colors are thus fairly limited for the geometry of the luminophore covered zone cannot be modified in large proportions and the total number of luminophore covered zones per elementary image point cannot become too great: thus, when three luminophores of different colors are used, each elementary image point cannot reasonably comprise more than three or four zones.
Furthermore, such balancing possibilities cannot be used for overcoming the differences found experimentally from one panel to another, for they can only be put into practice during manufacture of the panels.
The present invention solves the above mentioned problem in a simple and efficient way.